scholarly journals Combinatorial approach of in silico and in vitro evaluation of MLH1 variant associated with Lynch syndrome like metastatic colorectal cancer

2020 ◽  
Vol 40 (6) ◽  
Author(s):  
Komal Saleem ◽  
Tahir Zaib ◽  
Wei Ji ◽  
Chunhui Zhang ◽  
Qian Qin ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Lynch Syndrome ◽  
In Silico ◽  
Causative Gene ◽  
Dna Mismatch ◽  
Functional Studies ◽  
Whole Exome ◽  
Increased Risk ◽  
Prediction Approach

Abstract Colorectal cancer (CRC) is the third most developing cancer worldwide and Lynch syndrome (LS) accounts for 3–4% of CRC. Genetic alteration in any of DNA mismatch repair (MMR) gene is the major cause of LS that disrupt the normal upstream and downstream MMR events. Germline mutation of MLH1 in heterozygous state have an increased risk for CRC. Defective MMR pathway mostly results in microsatellite instability (MSI) that occurs in high percentage of CRC associated tumors. Here, we reported a patient with LS like metastatic CRC (mCRC) associated with other related cancers. Whole exome sequencing (WES) of the proband was performed to identify potential causative gene. Genetic screening validated by Sanger sequencing identified a heterozygous missense mutation in exon 12 of MLH1 (c.1151T>A, p.V384D). The clinical significance of identified variant was elucidated on the basis of clinicopathological data, computational predictions and various in vitro functional analysis. In silico predictions classified the variant to be deleterious and evolutionary conserved. In vitro functional studies revealed a significant decrease in protein expression because of stability defect leading to loss of MMR activity. Mutant residue found in MutL transducer domain of MLH1 that localized in the nucleus but translocation was not found to be significantly disturbed. In conclusion, our study give insight into reliability of combinatorial prediction approach of in silico and in vitro expression analysis. Hence, we highlighted the pathogenic correlation of MLH1 variant with LS associated CRC as well as help in earlier diagnosis and surveillance for improved management and genetic counselling.

scholarly journals Functional Characterization of a Missense Variant of MLH1 Identified in Lynch Syndrome Pedigree

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Tahir Zaib ◽  
Chunhui Zhang ◽  
Komal Saleem ◽  
Lidan Xu ◽  
Qian Qin ◽  
...  
Keyword(s):  
Lynch Syndrome ◽  
Functional Characterization ◽  
Family Members ◽  
Missense Variant ◽  
Chinese Family ◽  
Causative Gene ◽  
Bioinformatic Tools ◽  
Whole Exome

Lynch syndrome (LS) is the most common hereditary colorectal cancer (CRCs) inherited in an autosomal-dominant manner. Here, we reported a multigeneration Chinese family clinically diagnosed with LS according to the Amsterdam II criteria. To identify the underlying causative gene for LS in this family, whole-exome sequencing (WES) was performed. A germline missense variant (c.2054C>T:p.S685F) in exon 18 of MLH1 was successfully identified by WES. Sanger sequencing verified the results of WES and also confirmed the cosegregation of the MLH1 missense variant in all affected members of the family including two unaffected family members. Bioinformatic tools predicted the identified MLH1 variant as deleterious. Immunohistochemistry (IHC) staining showed loss of MLH1 and PMS2 protein expression. In vitro expression analysis also revealed that the identified MLH1 missense variant (c.2054C>T:p.S685F) results in reduced expression of both MLH1 and PMS2 proteins. Based on the American College of Medical Genetics and Genomics (ACMG) guidelines, the missense mutation c.2054C>T in MLH1 was classified as a “pathogenic” variant. Two unaffected family members were later recommended for colonoscopy and other important cancer diagnostic inspections every 1-2 years as both were at higher risk of LS. In conclusion, our findings widen the genotypic spectrum of MLH1 mutations responsible for LS. This study increases the phenotypic spectrum of LS which will certainly help the clinicians in diagnosing LS in multigeneration families. This study also puts emphasis on the importance of genetic counselling for the benefit of asymptomatic carriers of MMR gene variants who are at higher risk of LS.

scholarly journals Use of nivolumab for colon cancer with Lynch syndrome

2020 ◽  
Vol 22 (3) ◽  
pp. 114-119
Author(s):  
G. A. Khakimov ◽  
A. A. Tryakin ◽  
G. G. Khakimova
Keyword(s):  
Colorectal Cancer ◽  
Lynch Syndrome ◽  
Mismatch Repair ◽  
Dna Mismatch Repair ◽  
Checkpoint Inhibitors ◽  
Survival Rates ◽  
Stage Iv ◽  
Sporadic Colorectal Cancer ◽  
Dna Mismatch ◽  
Increased Risk

Lynch syndrome (LS), which occurs as a result of the defects in DNA mismatch repair, is characterized by an increased risk of colon, endometrial and urinary tract cancers. It is known that in case of colorectal cancer, the presence of high-frequency microsatellite instability (MSI-H) is associated with better survival rates, independent of other prognostic factors, including the stage of tumor development. Thus, in stage II sporadic colorectal cancer, MSI-H occurs in 22% of cases, in stage III in 12% of cases, and in stage IV only in 2% of cases. Regardless of the type of the tumor, immunotherapy using checkpoint inhibitors has been approved for treating patients with unresectable or metastatic tumors with deficient DNA mismatch repair (dMMR), this fact can be used as an approach to treatment patients with LS. The article describes the clinical observation of the patient with germline mutation in MLH1 gene, suffering from multiple primary malignancies of the colon, who has been receiving nivolumab for 26 months. This observation demonstrates the success of immunotherapy after sixth-line chemotherapy, showing the potential control of tumor growth in patients with LS.

TUMOUR PATHOLOGY PREDICTS MICROSATELLITE INSTABILITY IN A POPULATION-BASED SERIES OF COLORECTAL CANCER CASES

2008 ◽  
Vol 31 (4) ◽  
pp. 12
Author(s):  
A J Hyde ◽  
D Fontaine ◽  
R C Green ◽  
M Simms ◽  
P S Parfrey ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Lynch Syndrome ◽  
Microsatellite Instability ◽  
Population Based ◽  
Pathological Features ◽  
Predictive Tool ◽  
Entire Cohort ◽  
Dna Mismatch ◽  
Bethesda Guidelines ◽  
Revised Bethesda Guidelines

Background: Lynch Syndrome is an autosomal dominant trait that accounts forapproximately 3% of all cases of colorectal cancer (CRC). It is caused by mutations in DNA mismatch repair (MMR) genes, most commonly MLH1 or MSH2. These MMR defects cause high levels of microsatellite instability (MSI-H) in the tumours. MSI testing of all CRCs to identify potential Lynch Syndrome cases is not practical, so the Bethesda Guidelines, which use clinical and pathological features, were created to identify those tumours most likely to be MSI-H^1. In 2007 Jenkins et. al. created MsPath, a tool based on the pathological features described in the rarely used 3^rd Bethesda criterion, to improve prediction of MSI-H tumours among CRC cases diagnosed before age 60 years^2. Methods: We collected a population-based cohort of 716 CRC cases diagnosed before age 75 years in Newfoundland. For each of these cases we collected family history, performed MSI analysis, and scored a number of pathological features for the purpose of evaluating the accuracy of the Bethesda Criteria and MsPath at predicting MSI-H tumours. Results: Our work validates the MsPath tool in the Newfoundland population for the same age group used to create the tool. We found it identified MSI-H cases with a sensitivity of 95% and specificity of 35% in our population of CRCcases diagnosed before age 60 years (n=290). We also tested this tool on our older population of CRCcases, diagnosed at ages 60 to 74 years (n=426). We found it to be at least as predictive in this population,with a sensitivity of 95% and a specificity of 42%. We then used our entire cohort (N=716) to compare MsPath with the other Bethesda criteria.Bethesda criteria 1, 2, 4 and 5 together predicted MSI-H cases with a sensitivity of 67% and a specificity of 51%. MsPath was better at identifying these cases, with a sensitivity of 95% and a specificity of 39%. Conclusions: We conclude that MsPath can be extended to include patients diagnosed with CRC before age 75 years. As well, we have found that MsPath is a better predictive tool than the Revised Bethesda Guidelines for identifying MSI-H cases within a population-based setting of colorectal cancer. References: 1. Umar, A. et. al. J Natl Cancer Inst 2004;96:261-8 2.Jenkins, M.A. et. al. Gastroenterology 2007;133:48-56

scholarly journals Biallelic SORD pathogenic variants cause Chinese patients with distal hereditary motor neuropathy

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Hai-Lin Dong ◽  
Jia-Qi Li ◽  
Gong-Lu Liu ◽  
Hao Yu ◽  
Zhi-Ying Wu
Keyword(s):  
Ex Vivo ◽  
Protein Solubility ◽  
Chinese Patients ◽  
Hereditary Neuropathy ◽  
Motor Neuropathy ◽  
Causative Gene ◽  
Hereditary Motor ◽  
Functional Studies ◽  
Hereditary Motor Neuropathy

AbstractSorbitol dehydrogenase gene (SORD) has been identified as a novel causative gene of recessive forms of hereditary neuropathy, including Charcot–Marie–Tooth disease type 2 and distal hereditary motor neuropathy (dHMN). Our findings reveal two novel variants (c.404 A > G and c.908 + 1 G > C) and one known variant (c.757delG) within SORD in four Chinese dHMN families. Ex vivo cDNA polymerase chain reaction confirmed that c.908 + 1 G > C variant was associated with impaired splicing of the SORD transcript. In vitro cell functional studies showed that c.404 A > G variant resulted in aggregate formation of SORD and low protein solubility, confirming the pathogenicity of SORD variants. We have provided more evidence to establish SORD as a causative gene for dHMN.

scholarly journals Homozygous TRPV4 mutation causes congenital distal spinal muscular atrophy and arthrogryposis

2018 ◽  
Author(s):  
Jose Velilla ◽  
Michael Mario Marchetti ◽  
Agnes Toth-Petroczy ◽  
Claire Grosgogeat ◽  
Alexis H Bennett ◽  
...  
Keyword(s):  
Spinal Muscular Atrophy ◽  
Exome Sequencing ◽  
Whole Exome Sequencing ◽  
In Silico ◽  
Muscular Atrophy ◽  
Structural Modeling ◽  
Recessive Mutation ◽  
Homozygous Mutation ◽  
Functional Studies ◽  
Whole Exome

AbstractObjectiveThe objective of this study is to identify the genetic cause of disease in a congenital form of congenital spinal muscular atrophy and arthrogryposis (CSMAA).MethodsA 2-year-old boy was diagnosed with arthrogryposis multiplex congenita, severe skeletal abnormalities, torticollis, vocal cord paralysis and diminished lower limb movement. Whole exome sequencing was performed on the proband and family members. In silico modeling of protein structure and heterologous protein expression and cytotoxicity assays were performed to validate pathogenicity of the identified variant.ResultsWhole exome sequencing revealed a homozygous mutation in the TRPV4 gene (c.281C>T; p.S94L). The identification of a recessive mutation in TRPV4 extends the spectrum of mutations in recessive forms of the TRPV4-associated disease. p.S94L and other previously identified TRPV4 variants in different protein domains were compared in structural modeling and functional studies. In silico structural modeling suggests that the p.S94L mutation is in the disordered N-terminal region proximal to important regulatory binding sites for phosphoinositides and for PACSIN3, which could lead to alterations in trafficking and/or channel sensitivity. Functional studies by western blot and immunohistochemical analysis show that p.S94L reduces TRPV4 protein stability because of increased cytotoxicity and therefore involves a gain-of-function mechanism.ConclusionThis study identifies a novel homozygous mutation in TRPV4 as a cause of the recessive form of congenital spinal muscular atrophy and arthrogryposis.

scholarly journals Recent advances in understanding Lynch syndrome

F1000Research ◽  
2016 ◽  
Vol 5 ◽  
pp. 2889 ◽  
Author(s):  
Sherief Shawki ◽  
Matthew F. Kalady
Keyword(s):  
Colorectal Cancer ◽  
Lynch Syndrome ◽  
Correct Diagnosis ◽  
Diagnostic Testing ◽  
Gene Mutations ◽  
The United States ◽  
Cancer Syndrome ◽  
Dna Mismatch ◽  
Recent Developments ◽  
Risk Patients

Colorectal cancer affects about 4.4% of the population and is a leading cause of cancer-related death in the United States. Approximately 10% to 20% of cases occur within a familial pattern, and Lynch syndrome is the most common hereditary colorectal cancer syndrome. Lynch syndrome is a hereditary predisposition to forming colorectal and extracolonic cancers, caused by a germline mutation in one of the DNA mismatch repair genes. Identifying at-risk patients and making a correct diagnosis are the keys to successful screening and interventions which will decrease formation of and death from cancers. Knowledge of the genetics and the natural history of Lynch syndrome has continued to be uncovered in recent years, leading to a better grasp on how these patients and their families should be managed. Recent developments include the approach to diagnostic testing, more precise definitions of the syndrome and risk stratification based on gene mutations, surgical decision-making, and chemoprevention.

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